Caulking masses based on silicone are used to a large extent for sealing purposes, as well as for bonding and adhesive purposes. Due to their inorganic components, they have a certain fire-inhibiting effect, which can be improved by the addition of known flame-retarding materials.
It has previously been proposed to use foamable silicone compositions for connecting parts or for sealing purposes, for example, for sealing pipeline and wiring openings as well as door or window frames in masonry or gaps or cracks in masonry and the like. Compared to other foams, such as polyurethane foams, which burn or "melt" in the event of a fire, the silicone foams have the advantage of higher stability under load. In addition, silicone foams do not release any toxic gases in the event of a fire. However, the behavior during fire conditions is by no means satisfactory. Soon after the outbreak of a fire, cracks develop in the "carbonizing" layer on the surface facing the fire. These cracks have a tendency soon to become deeper and finally they permit the fire to break through. The attempt to counteract the spread of the fire thus ultimately fails.